The present invention generally relates to the production of printed images on a substrate, and more particularly to a high-efficiency process for delivering printed images to a substrate which are clear, vivid, and water-fast.
In recent years, many different substrates (e.g. "print media materials") have been developed for a wide variety of applications. These substrates were specifically designed for use with high-definition printing systems that are capable of delivering monochromatic or multi-colored images in a rapid manner. Thermal inkjet systems are especially important in this regard. Printing systems using thermal inkjet technology basically involve a cartridge which includes at least one ink reservoir chamber in fluid communication with a printhead having a plurality of resistors therein. Selective activation of the resistors causes thermal excitation of the ink and expulsion of the ink from the cartridge. Representative thermal inkjet systems are discussed in U.S. Pat. No. 4,500,895 to Buck et al.; U.S. Pat. No. 4,771,295 to Baker et al.; U.S. Pat. No. 5,278,584 to Keefe et al.; and the Hewlett-Packard Journal, Vol. 39, No. 4 (August 1988), all of which are incorporated herein by reference.
Whether a thermal inkjet printing system or other type of printing apparatus is employed, one substrate of current interest involves a structure which consists of multiple layers affixed together to form a single, integrated unit. Typical substrates of this type normally include (1) a backing layer usually manufactured from one or more organic polymer compositions; and (2) an ink-absorbent layer made from a composition that is specifically designed to retain and absorb ink materials. These substrates are commercially available from a number of sources including the Hewlett-Packard Company of Palo Alto, Calif. (USA) under the product designations C3836A and C3834A. Substrates of this type are currently used for a number of different purposes. These purposes range from the preparation of "transparencies" for overhead projector use to the production of high-quality printed sheets while may be employed for display purposes in many different technical fields.
Regardless of the particular printing method that is selected to deliver ink materials to a multi-layer substrate of the type listed above, a number of important considerations exist which directly relate to the overall quality of the final printed image. The printed image must be vivid (particularly if multi-color designs are involved) and clear with a high level of definition. The word "vivid" (which is also known as "high-chroma") specifically involves a situation in which the printed image (comprised of one or more colors) is bright, crisp, and clearly defined from one color region to another. In addition, of primary importance is another factor which greatly influences the overall print quality and stability of the final printed product. Specifically, the printed image on the substrate must be water-fast. The term "water-fast" as used herein shall signify a printed image which does not smear, bleed, run, or fade when exposed to moisture (e.g. water and/or water-based materials). If the printed image on the substrate is not sufficiently water-fast it will become distorted, indistinct, and unclear during and after contact with moisture. The production of water-fast images is therefore of considerable importance in all types of printing systems including those which use thermal inkjet technology.
Prior to development of the present invention, a need existed for materials and processes which were capable of producing clear, vivid, and water-fast printed images on a substrate of the type listed above (e.g. which includes a polymeric backing layer and an ink-absorbent layer positioned on the backing layer). A need also remained for a system in which these benefits could be achieved using many different printing systems, including those which incorporate thermal inkjet technology. The present invention satisfies this need in a unique and effective manner which enables the creation of clear, vivid, and water-fast printed images on the multi-layer substrates of primary interest as discussed above. Likewise, the claimed invention is especially appropriate for use in connection with thermal inkjet systems and other printing methods in which ink materials are dispensed from a cartridge unit having one or more self-contained ink ejectors therein. Accordingly, as discussed in considerable detail below, the claimed invention represents an important advance in printing technology and satisfies a number of long-felt needs.